In the Settings->Discussion page, authors of a post can use the checkbox Email me whenever – Anyone posts a comment.

But this does not send an email as well to the site admins. In blogs where you have a number of guest authors, you may want to be informed about all the new comments so you can respond (if the author is missing) or just participate in the discussion.

As a site admin myself, I was missing many comments. This means plenty of missing opportunities to engage with your audience.

To solve this situation, the plugin adds a new checkbox in the Discussion page. If checked, admins will get an alert email for new comments.